Balanced split sun assemblies with integrated differential mechanisms, and variators and drive trains including balanced split sun assemblies

Abstract

A balanced split sun assembly with an integrated differential mechanism allows power to be transferred from a sun assembly to a plurality of ball planets, or allows power to be transferred from a plurality of ball planets to a sun assembly, while minimizing sliding, spin, axial pull, or other unwanted effects on the sun assembly. A differential mechanism, including offset mechanisms, allows torque to be divided between multiple split sun rolling elements. Variations in design of a split sun assembly allow for ease of manufacture, ease of assembly, and ease of adjustment.

What is claimed is: 
     
       1. A variator, comprising:
 a central axle defining a longitudinal axis; 
 an array of ball planets rotatable about the longitudinal axis; 
 a first ring in contact with the array of ball planets and orbital about the longitudinal axis, the first ring being on a first side of the array of ball planets; 
 a second ring in contact with the array of ball planets and orbital about the longitudinal axis, the second ring being on a second side of the array of ball planets; 
 a first sun rolling element with a first axis coincident with the longitudinal axis, the first sun rolling element shaped for contact with the array of ball planets; 
 a second sun rolling element with a second axis coincident with the longitudinal axis, the second sun rolling element shaped for contact with the array of ball planets; and 
 a torque differential mechanism coupled to the central axle and coupled to each of the first sun rolling element and the second sun rolling element, 
 wherein power is transferred from the central axle to the torque differential mechanism, 
 wherein the torque differential mechanism transfers a first torque to the first sun rolling element and a second torque to the second sun rolling element, and 
 wherein each of the first sun rolling element and the second sun rolling element transfer power to the plurality of ball planets. 
 
     
     
       2. The variator of  claim 1 , wherein the torque differential mechanism comprises a plurality of rollers interposed between the first sun rolling element and the second sun rolling element. 
     
     
       3. The variator of  claim 2 , wherein the torque differential mechanism is offset axially from the first and second sun rolling elements. 
     
     
       4. The variator of  claim 2 , wherein the torque differential comprises
 a first portion configured to retain the rollers 
 a second portion extending axially and having an axial length; and 
 a third portion extending radially and having a radial length, wherein the first portion, the second portion, the third portion, and the central axle define a volume having a fluid capacity. 
 
     
     
       5. The variator of  claim 1 , wherein the differential mechanism comprises a bevel gear mechanism coupled to the central axle, wherein a first bevel gear is coupled to the first sun rolling element and a second bevel gear is coupled to the second sun rolling element. 
     
     
       6. A drivetrain comprising:
 a variator comprising:
 a central axle coupled to a power source; 
 an array of ball planets orbital about the central axle, the central axle defining a longitudinal axis; 
 a first ring in contact with the array of ball planets and rotatable about the longitudinal axis, the first ring being on a first side of the array of ball planets; 
 a second ring in contact with the array of ball planets and rotatable about the longitudinal axis, the second ring being on a second side of the array of ball planets; 
 a first sun rolling element rotatable about the central axle, the first sun rolling element shaped for contact with the array of ball planets; 
 a second sun rolling element with an axis coincident to the central axle, the second sun rolling element shaped for contact with the array of ball planets; and 
 a torque differential mechanism coupled to each of the first sun rolling element and the second sun rolling element, 
 wherein power is transferred from the central axle to the torque differential mechanism, 
 wherein the torque differential mechanism transfers a first torque to the first sun rolling element and a second torque to the second sun rolling element, 
 wherein each of the first sun rolling element and the second sun rolling element transfer torque to the plurality of ball planets. 
 
 
     
     
       7. The drivetrain of  claim 6 , wherein the variator is coupled to the power source via a shaft extending through the variator, wherein torque transferred from the first sun rolling element is equal to torque transferred from the second sun rolling element. 
     
     
       8. The drivetrain of  claim 6 , wherein the variator is coupled to a power load via one of the first or second rings.